It is not uncommon to find a power supply having a plurality of slots for receiving individual power supply modules. The modular architecture provides several advantages, including, an increase in the level of power that may be delivered to a load and an increase in the overall reliability of the power supply by sharing the load requirements among a plurality of redundant power supply modules. Additionally, the modular architecture enhances the flexibility of the power supply by allowing individual modules to be replaced to accommodate changes in the power supply requirements. Finally, the modular architecture provides a robust system whereby untrained personnel can rapidly replace failed modules.
Conventionally, the power supply may employ multiple converters in separate modules that convert an AC or DC input voltage to a DC output voltage. Again, the power supply may employ multiple converters in separate modules to increase the overall capacity and reliability of the power supply. The converters, in such a system, share the load to, among other things, evenly distribute stresses among the separate modules, while providing a regulated output to the load. Also, when a failure occurs in a modular system, it is possible to identify and shut down the failed unit without affecting the other parallel connected units, thereby minimizing the overall effects on the output of the power supply.
Structurally, the modular power supply is housed in a chassis or framework that provides support for shelves that contain the individual power supply modules. The chassis generally includes U-shaped uprights that the shelves and other equipment of the modular power supply are attached to. The chassis further includes compartmentalized rear and side panels formed of sheet metal to cover the power supply modules and other components that make-up the modular power supply. The chassis and panels form an exo-skeletal cabinet for the modular power supply. The chassis is typically a freestanding framework with the panels added for aesthetic and safety purposes. The shelves accommodate multiple power supply modules.
The modular power supply further includes a power distribution system that distributes power to and from the power supply modules therein. For instance, commercially provided AC power derived from the local utility is fed into the power supply modules, converted by the power supply modules (e.g., in this case, the power converter modules) and DC power is provided to a load coupled to the modular power supply via a power bus architecture. The input and output power, therefore, is distributed through the modular power supply by the power distribution system.
The power bus architecture generally includes a plurality of horizontal bus bars couplable to the power supply modules. The horizontal bus bars are typically supported by the horizontal braces of the chassis. The horizontal bus bars are coupled together by a vertical main power bus. In addition to coupling the horizontal bus bars together, the main power bus provides a path for the output power to the load. Therefore, the power bus architecture of the modular power supply includes a plurality of horizontal bus bars and a vertical main power bus.
The construction of the modular power supply occurs according to the following general steps. First, the chassis is constructed providing the structural framework for modular power supply. Second, the power distribution system is coupled to the frame. Third, the power supply modules are evenly placed on trays that are individually loaded into the chassis proximate the horizontal braces. In conjunction with loading the trays into the chassis, the power supply modules are coupled to the AC input and control terminals and to the horizontal bus bars. Finally, the sheet metal panels may be placed about the chassis to complete the modular power supply.
While the present design of the cabinet and power distribution system provides a workable construction for a modular power supply, there are limitations with such designs. The power supply modules dissipate heat in the process of generating or converting power. To promote the safe and efficient operation of the modular power supply, the heat must be removed from within the cabinet. The horizontal bus bars impede the airflow within the chassis. Consequently, powerful fans capable of moving a sufficient quantity of air through the chassis must be provided in connection with the power supply modules.
In combination therewith, the chassis of the modular power supply must be of sufficient depth to provide a channel that facilitates the removal of the exhaust air from the power supply modules. The modular power supply, therefore, occupies a great deal of valuable floor space to accommodate the depth requirements compelled with the use of the horizontal bus bars of the power distribution system. Additionally, the present power bus architectures require added hardware and structural framework to accommodate the power supply modules of the modular power supply.
Accordingly, what is needed in the art is a power distribution system having a simplified power bus architecture that facilitates a reduction of the overall footprint of the modular power supply by minimizing airflow restrictions therethrough.